If the functioning of all three divisions is suspended, death ensues, and if the two higher divisions are entirely placed out of action, and the lowest only functions, with enfeebled force we get a state of coma, in which the patient lies absolutely motionless and unconscious, and out of which he cannot be roused. In this state, the functions of organic life alone continue, and the)' only with greatly diminished activity. Such are the coma of apoplectic states, alcoholic poisoning, etc. In these cases the condition depends upon destruction of the properties of the highest nervous arrangements, either from gross lesion or from chemical changes. One sees a somewhat similar condition produced by exhaustion of nervous elements in post-epileptic coma.

In natural, sound, dreamless sleep, we also get the action of the two highest divisions of the nervous system completely suspended, but the sleeper can be easily aroused, because the suspension depends to a great extent on cortical inhibition. In sleep accompanied by dreams there is incomplete suspension, and certain areas of the highest division continue to function apart from their usual combinations, and therefore more or less unintelligently.* If the action of the discharging centres is energetic, it will, as we have seen, be accompanied by movements, and somnambulism may result. In hypnosis brought about by suggestion, cessation of function does not depend upon exhaustion, but is the result of inhibition, and is not, therefore, followed by exhaustion; on the contrary, it refreshes the system in the same way as, and in a marked degree more than, natural sleep. The awakening is immediate, and depends upon the removal of the inhibitory influence. If the phenomenon depended upon exhaustion of the nervous elements, time and rest would be required for recuperation, and this we know is not the case.

Hypnotism cannot, I believe, produce epilepsy de novo, even though it be employed ignorantly and recklessly; but under such circumstances it may determine a latent tendency. In hypnotizing epileptics, it is by no means uncommon to see a slight fit produced by the process. The same applies to the administration of chloroform and the ingestion of an excessive quantity of alcohol, and tends to show that in each case the agent acts on the cells of the same cortical area. The view put forth by Hughlings Jackson, in discussing epileptic convulsions, that the highest level of the cortex not only subserves the psychical processes and constitutes the physical substratum of consciousness - volition, thought, emotion, judgment, etc. - but also represents, though very indirectly, muscular movements and organic functions, throws an important light on the action of hypnotic suggestion on vital processes.

* An experiment referred to by Heidenhain and also by Gerald Yeo serves to show how completely the higher cerebral faculties are in abeyance in the profounder states of hypnotism. Both these authors refer to the production of the ' echo voice.' This is produced by stroking the back of the subject's neck with the hand, when he will at once repeat any words said to him. The effect produced is curiously like that experienced in listening to a phonograph. The subject may be perfectly uneducated, and yet he will repeat accurately after the reciter an ode of Horace or the chorus from a Greek play (compare case on p. 81). An analogous experiment on a frog, deprived of its brain, illustrates how completely the profoundly hypnotized subject may be said to be ' robbed of his cerebral hemispheres.' If the frog's flanks be gently stroked, it will croak, not continuously, but each stroke will be followed by a croak, so that Yeo supposes there is an unknown relation between certain sensory surfaces and the speech centres {op. cit., p. 13).

Another experiment is that of making a person speak by placing the hand over the left temple, the idea being, of course, to stimulate Broca's speech centre underneath. The subject will at once answer if spoken to; but if the same place be again touched he will as suddenly become silent, though he may be in the middle of a word or sentence. I have seen several such experiments, but have hitherto been unable to repeat them on unprepared subjects. Heidenhain and the other writers of more than a few years ago were not so fully alive to the extraordinary readiness of the subject to act upon suggestion, and to take advantage of the smallest hint as we are now. The subject's mind is like an extra sensitive plate. As the faintest light will affect the one, so will the slightest hint influence the other. Without denying that somatic reactions may occur in the hypnotic state, I think we should be very cautious in accepting them.

The action of hypnotism is probably exerted entirely on the highest centres, and if these represented only mental processes, it would be difficult to understand how by affecting them we could produce the changes in nutrition and function which undoubtedly result from hypnotic suggestion. But if it be correct to suppose that we can influence the functions of the lower centres by acting directly on the highest, that by influencing the hierarchy we can modify the behaviour of the subordinate functionaries of the body, we hold a key to the solution of the problem. According to Liebeault, we attack disease and affect function in gross by acting upon the starting-point and centre of vital processes (the cerebrum), instead of addressing ourselves to the treatment of their peripheral manifestations, and attacking these in detail by drugs.

I believe all physiologists are now agreed as to the effect the higher centres of the cerebral cortex are able to exert over the lower nervous arrangements. Professor Morselli of Genoa, writes: ' Every mental state and every act of the intelligence has its centrifugal equivalent.' * 'The mental functions act as supreme and constant regulators of all the nervous processes, even of those which are purely automatic and are not attended with consciousness. Though they are withdrawn from the direct influence of the psychic activity, they are nevertheless dependent on it.' *

* ' Fisiopsicologia dell' ipnotismo,' p. 14.